does anyone know if these multi-caliber setups are imported into the US at all?

A few were imported a long time ago by Springfield Armory.  I've never seen one after that, even on the used market.  The best you will find, most likely, is the Springfield Omega 10MM.  Harris Gunworks and Federal Ordnance (both now defunct) imported the upper assemblies too.  Back in the '80's I heard some not so falttering reports of their reliability.  

Quoted: A few were imported a long time ago by Springfield Armory.  I've never seen one after that, even on the used market.  The best you will find, most likely, is the Springfield Omega 10MM.  Harris Gunworks and Federal Ordnance (both now defunct) imported the upper assemblies too.  Back in the '80's I heard some not so falttering reports of their reliability.

they were crap?

I can't say if they were crap.  I know that the Omegas in 10mm that I've seen were well made, but there was a guy who shot IPSC here that had one that would not run.  Who knows what he did to it, if anything.  I would think that the Omegas will run fine as long as they are properly sprung.  The dual extractor setup is somehting I have not experienced.  

ah..... yeah I'd guess he did something to it personally..... Peters-Stahl pistols look to be VERY well made

I owned a 10mm Springfield Omega, NIB, back around 1992 or so. Initially, the dual extractor  system was improperly tensioned resulting in FTE on a frequent basis. Back to Springfield. Same issue when it came back. I looked a little closer and determined that the "inner" of  the dual extractors had MORE spring tension than the outer "external" extractor, resulting in MORE tension on the rim near the ejector, hindering ejection. Didn't make sense to me.

After essentially swapping springs (outer extractor with MORE tension), it ran fairly well. It was an accurate pistol and a pleasure to shoot with full power 180gr 10mms.  Mine was a 6" ported longslide.

I ended up trading it a number of years ago, and now regret it.

Quoted: I owned a 10mm Springfield Omega, NIB, back around 1992 or so. Initially, the dual extractor  system was improperly tensioned resulting in FTE on a frequent basis. Back to Springfield. Same issue when it came back. I looked a little closer and determined that the "inner" of  the dual extractors had MORE spring tension than the outer "external" extractor, resulting in MORE tension on the rim near the ejector, hindering ejection. Didn't make sense to me. After essentially swapping springs (outer extractor with MORE tension), it ran fairly well. It was an accurate pistol and a pleasure to shoot with full power 180gr 10mms.  Mine was a 6" ported longslide. I ended up trading it a number of years ago, and now regret it.

There is a perfect one that is hard chromed for sale on all the boards.  It's here, Glock Talk, and GunsAmerica for $1,000.  Though the price is steep, I see crappy ones at that price all the time, and this one is perfect.

I don't regret it enough to buy another one